Shimano Ultegra RTR Disc Brake has additional aluminium cooling funs to reduce rotor surface temperature about 150 degrees Celsius compared to all-steel rotors. It features has a 3 layer structure.
Features:
-A centre-lock disc
-160mm rotor size
-Weighs 128g
-Aluminium spider
-Stainless steel outer layers
-Aluminium core and cooling fins.